Dietary Cysteine and Methionine Deprivation (CMD) in Glioma Patients

This pilot study looks at how certain diet changes affect the body in patients with recurrent brain tumors (glioma) who are planning to have standard treatment like radiation or surgery. Up to 30 patients will be randomly assigned to either a regular diet or a special diet that limits two nutrients (cysteine and methionine) for 2, 4, or 7 days before their treatment. Patients will be monitored for side effects using blood tests and questionnaires, and patients will keep a diary to track how well they follow the diet. Blood and urine samples will be used to see how the diet affects the body. Tumor samples (from surgery) will help researchers study how the cancer cells behave, and stool samples will be used to look at gut bacteria. This is a randomized, blinded interventional pilot study to measure glutathione metabolite levels with a cysteine/methionine deprivation (CMD) diet in glioma patients. A menu of pre-prepared meals will be provided to subjects that consist of either a control diet or a CMD diet. The CMD diet will be implemented simultaneously in 2 cohorts of participants with recurrent glioma. The primary objective will be to measure the metabolic state of glioblastome multiforme tumor cells through dietary restriction of the sulfur-containing amino acids (SAA), cysteine/cystine and methionine. Patient from cohort A can later be included in Cohort B if applicable. Patients will be followed for progression free survival and overall survival for up to 1 year, or until they discontinue or are removed from the study for exploratory endpoints.